156: Dimethoxycurcumin Induces Global DNA Hydroxymethylation & Increases the Activity of TET Enzymes in Leukemia Cells

Statement of Purpose: Dimethoxycurcumin (DMC) is a metabolically stable analog of curcumin that demonstrated antitumor activity in leukemia cells. Although its exact mechanism of action is not clear, it induces a variety of epigenetic histone modifications in leukemia cells that may contribute to its antitumor effect. DNA hydroxymethylation (5hmC) is an epigenetic mark produced from the oxidation of 5-methylcytosine (5mC) by the family of enzymes known as Ten-Eleven Translocation (TET). 5hmC plays a role in regulating gene expression that is distinct from the closely related 5mC. In this study, we tested the effect of DMC and its parent compound curcumin (Cur) on global 5hmC and on the activity of the TET isoforms that catalyze the conversion of 5mC into 5hmC.

Description of Methods & Materials: HL60 and U937 leukemia cell lines were treated with different concentrations of Cur and DMC for 48 hours. Nuclear extracts were used to measure the activity of TET isoforms using a fluorometric ELISA-based assay and an antibody against 5hmC. DNA extracts were used to quantitate the epigenetic mark 5hmC using a fluorometric assay that uses a specific antibody against 5hmC.

Data & Results: Global 5hmC was significantly increased upon treatment with either Cur or DMC in U937 cells. HL60 cells demonstrated similar increase in global 5 hmC with Cur only but not DMC (Figure 1). Concordantly, both drugs increased the activity of the TET enzymes in both HL60 and U937 (Figure 2).

Interpretation, Conclusion or Significance: We identified a novel epigenetic target for Cur and its analog DMC that may affect gene expression and the antitumor activity of these compounds. Increased 5hmC level indicates that both drugs induce active DNA demethylation, which may lead to activation of epigenetically-silenced tumor suppressor genes. Analysis of the changes in 5hmC level across the whole genome is currently under investigation to identify the genes showing increase in 5hmC level.

Disclosures: None